Method and a device for the regulation of the web tension in a multi-web system

ABSTRACT

The tension of a web in a multi-web system is regulated. At least two webs initially run through a first processing step independently of each other and are subsequently combined with each other to form one resultant web strand. The web tensions of these two initially independent webs are adjusted to each other through a first regulation process. Each of these webs has its web tension regulated on the separate web path by a dedicated second regulation process which is different from the first regulation process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. patent application is the U.S. national phase, under 35 USC371, of PCT/DE2003/002998, filed Sep. 10, 2003; published as WO2004/031059 A2 and A3 on Apr. 15, 2004, and claiming priority to DE 10245 587.2 filed Sep. 27, 2002 and to DE 103 03 122.7, filed Jan. 27,2003, the disclosures of which are expressly incorporated herein byreference.

FIELD OF THE INVENTION

The present invention is directed to methods and to a device forcontrolling the web tension in a multi-web system. Initially, two websare each processed separately. These two webs are subsequently combinedinto a strand.

BACKGROUND OF THE INVENTION

A method for controlling the web tension of several webs is known fromEP 0 837 825 A2. By use of the respective web tension of several webs,their web tension levels, in relation to each other, are regulated by aregulation based on fuzzy logic.

A method for controlling web tensions in the course of multi-weboperations is known from DE 100 27 471 A1. Absolute and relativetensions of the webs, in relation to each other, are initially set atthe hopper inlet. This is preferably performed by the respective draw-indevice.

DE 42 33 855 discloses a device for controlling sheets in respect to thepresence of a single or a multiple sheet. The evaluation of measuredvalues takes place here on the basis of fuzzy logic.

SUMMARY OF THE INVENTION

The object of the present invention is directed to providing methods anda device for controlling the web tension in a multi-web system.

In accordance with the present invention, this object is attained by theuse of separate global and local control processes. A first, globalprocess controls the tensions of the two webs with respect to eachother. A second, local process controls the tension in each of the twowebs separately.

The present invention provides a system for the automatic regulation ofthe web tension for multi-web processing machines, and in particular,for rotary printing presses. Because of its closed-loop regulation, thesystem of regulation in accordance with the present inventionconstitutes a considerable further development in comparison to webtension control systems customary in present in rotary printing presses.The system is particularly advantageous for triple- or double-widthprinting presses.

The regulation concept of the present invention, which is based on fuzzylogic, makes an innovative contribution to increased productiondependability and to constant quality in a production process which, inview of costs, is increasingly directed toward less waste and towardfewer manual interventions. The regulation process of the presentinvention aids the operator during start-up of the press, reduces hisparticipation in the course of controlling the web tension during theproduction run, and makes a contribution to increased stability in allphases of the production.

On its way through the rotary printing press, from the initial rollchanger via the draw-in unit, through the printing units and thesuperstructure, and into the folding apparatus, a paper web undergoesdifferent states of tension, or tension relief or tension profile. Thesort of paper used, such as, for example, the manufacturer, grammation,or paper type, the repeated application of printing ink, and possibledampening water in the course of the offset process, the driven tractionelements, such as in the draw-in unit with or without compensatingrollers, traction rollers, hopper inlet rollers, as well as speedchanges, affect the actual tension profile of the paper web inside thepress. The regulation of a constant web tension during multi-weboperations is even more demanding and complex. In such multi-weboperations, the relative tension of the individual paper webs, inrelation to each other, at the superstructure, at the hopper inlet andin the folding apparatus is of importance for maintaining optimal webrunning and printing conditions.

In modern newspaper offset printers, web tension systems, on the basisof PID control devices, have already been realized in the area of theroll changers and draw-in units with a compensation roller. Thedownstream-situated traction devices in the press, typically downstreamof the printing groups and in the hopper inlet, however, are notcomprehensively included and regulated. Therefore, the coupling of thetraction elements corresponding to the production situation, to form acomprehensive, self-regulating web tension system, is a particularadvantage of the present invention.

By the provision of the intelligent web tension regulation, inaccordance with the present invention, it is intended to assure anoptimal web tension profile of each individual paper web within thepress, as well as to assure an optimized tension profiles of theindividual paper web, in relation to each other, in order to increasethe start-up dependability, by the provision of fewer down times as aresult of malfunctions, to achieve a uniform print quality, by fewerdifferences in registration, and to improve the running dependability ofthe press during multi-web operations.

With the present regulation of the subject invention, the software, onthe basis of fuzzy logic, sets the optimum tension level within thepaper webs as a function of the situation at the hopper inlet and as afunction of the respective paper profiles, and performs the optimalmatching of the webs to each other. The behavior that is typical for atype of each paper web is taken into consideration by use of the paperprofiles, i.e. by the use of available information, for exampletension-elongation characteristics, regarding the behavior of thedefined sort of paper. The knowledge of experts has been stored in thesystem for the rapid fixation of the setting logic.

The intelligent control system directly regulates the actually measuredtension values of the paper web in the processing press, rather than viamotor moments that are indirectly based on elongation measuring andcontrol. This results in advantages with respect to efficiency, as wellas to positive effects on waste, on production costs and on operationalergonomics.

It is an important point of the present invention, that the regulation,based on fuzzy logic technology, employs expert knowledge, and theoperator no longer must perform settings. The measured values regardingthe production are obtained by “shopping” and the appropriate units foraffecting the tension are directly addressed. In contrast to a discretecontrol device, with the present regulation system, an ideal totalsolution is almost always found without having to exactly maintain adefined regulation value, and a total solution, as with a discretecontrol device, could possibly not be obtained by the use of it. Thisapplies, in particular, to the control device dealing with the singleweb, which is provided with a specification from the control devicedealing with all webs. However, it is advantageous if the last mentionedcontrol device operates, by the use of fuzzy logic, in order to specify,if required, compromise solutions for conditions to the first mentionedcontrol device.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are represented in thedrawings and will be described in greater detail in what follows.

Shown are in:

FIG. 1, a schematic depiction of a printing press with several webs, in

FIG. 2, a schematic representation of a regulation with two controlprocesses, in

FIG. 3, a schematic representation of the regulation of the printingpress shown in FIG. 1, in

FIG. 4, a graphic representation of the progress of the web tensionalong its path, in

FIG. 5, a flow diagram of the web-related local control process inaccordance with the present invention, in

FIG. 6, a schematic representation of an allocation diagram, and in

FIG. 7, a flow diagram of the multi-web-related global control processof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Paths of several webs, such as at least two webs B1, B2 and for example,of four webs B1, B2, B3, B4 of material, for example of four paper websB1, B2, B3, B4, through a processing press, and in particular, through aprinting press, are shown schematically in FIG. 1. Also shown areschematically represented units, which substantially affect the webtension while the webs are passing through the press.

The web B1, B2, B3, B4, which will be explained, by way of example, inconnection with the web B1, is fed in from a supply device 01, forexample a roll changer 01, and passes through at least one tractiondevice, or braking device 02 for its conveyance and for setting of a webtension, for example a draw-in unit 02, before it passes through aprocessing stage 03, such as, for example, at least one printing unit 03having one or several printing groups. The draw-in unit 02 cansimultaneously represent an actuating member 02 for setting the tensionupstream of the printing unit 03. Following a last print locationassigned to the web B1, the latter passes through a measuring location04, nDE, which is situated downstream of printing unit 03 fordetermining the web tension. The web B1 thereafter passes through anactuating member 05 which is adapted for affecting the web tension, suchas, for example, a traction roller 05, or a roller/traction group 05.Turning bars and longitudinal cutting devices can be arranged in asuperstructure, which is not specifically represented, by the use ofwhich, either uncut webs B1 can be turned or tipped, or webs B1 can befirst cut and then turned or tipped. Prior to the entry of the web B1,or of the partial webs into a so-called harp 07, which is a plurality ofdeflection rollers assigned to several webs B1, B2, B3, B4, or topartial webs, a measuring location 06, vTE upstream of the hopper entry,for determining the web tension is provided for each web B1 or for everypartial web. The web tension measuring location 04, characterized as“downstream of the printing unit,” therefore means a measuring location04 located upstream of the actuating member, or traction element 05following the printing unit 03, or at least upstream of a possiblyprovided cutting or turning device. Following the harp 07, the web B1,or its partial webs, together with other webs B2, B3, B4 or theirpartial webs, is brought together into one or several web strands 13,and passes a further actuating member 08 affecting the web tension, suchas, for example a traction roller 08 or a roller/traction group 08, suchas, for example, a so-called hopper inlet roller 08, before the strand13 is longitudinally folded by one or by several hoppers 09, forexample. Therefore, the web tension measuring location 06 “upstream ofthe hopper inlet or harp” means a measuring location 06 for the singleweb or for a partial web prior to the bringing together of plural websor plural partial webs at the hopper inlet roller 08, or at a differentroller, located upstream and assigned to several webs, and downstream ofthe traction element 05 or, if provided, downstream of a cutting and/ora turning device. If the product is not wound up again, the webs B1, B2,B3, B4, or the partial webs in the strand 13 pass through a furtheractuating member 10 affecting the web tension, such as a furthertraction roller 10 or a roller/traction group 10, or folding tractionrollers 10, and are transversely folded, at least once, in at least onefolding apparatus 11. The previously-mentioned draw-in unit 02 has anactuating member 16 affecting the web tension, such as, for example atraction roller 16, or a roller/traction group 16, or a compensatingroller 16 and possibly a separate measuring location 14 for determiningthe web tension, vDE: upstream of the printing unit 03. The actuatingmember 16 and the measuring location 14 can also be arranged between theroll changer 01 and the printing unit 03 without being combined into adraw-in unit 02. The separate measuring location 14 can be omitted, ifadequate information regarding the prevailing web tension is provided bythe actuating member 16, which may be, for example, an actuating member16 which can be actuated by the use of a pressure medium.

In the printing press represented schematically in FIG. 1, webs B1, B2,B3, B4 from printing units 03 arranged on different sides of the hopper09, are conducted, by way of example, to the hopper 09. The hopperstructure can have several hoppers 09 next to and/or underneath eachother, and several strands 13 made of the webs B1, B2, B3, B4 can beconducted to more than one folding apparatus 11. Furthermore, the websB1, B2, B3, B4 need not each pass through a printing unit 03 in theschematically represented manner, but instead can, for example, afterpassing through a portion of a printing unit 03, be conducted out of itand can be conducted either immediately to the superstructure, or can beconducted to another printing unit 03 for further processing. However,it is essential that the web tension measuring locations 04, 06, 14, andthe actuating members 05, 10, 16 are or will be assigned to the webs B1,B2, B3, B4 for their regulation, which will be explained in greaterdetail below.

In FIG. 1, the web tension signals S1.1, S1.2, S1.3 from the web B1, orS2.1, S2.2, S2.3 from the web B2, etc., which are obtained by the webtension measuring locations 04, 06, 14, are indicated by arrows. Asignal S1.0, S2.0, S3.0, S4.0, indicated in dashed lines, can beobtained from a measuring location which is not specifically identified,and which describes the web tension, can be obtained also in the area ofthe roll changer 01. Furthermore, the preset values for the actuatingmembers 16, 05, in the form of signals S1.11, S1.12 for the web B1, orS2.11, S2.12 for the web B2, etc. are represented by arrows. Forexample, the signal Sx.11 represents a preset value or a desired valuefor the web tension in the draw-in unit 02, and the signal Sx.12represents a preset value or a desired value for the advance of thetraction roller 05. The signals S0.13, S0.14 represent the preset valuesor desired values, for example the advance, of the actuating members 08and 10. A possibly existing preset value or desired value for the webtension in the area of the roll changer 02 is identified by S1.10 forthe web B1, with S2.10 for the web B2, etc.

The printing press in FIG. 1 has a control system 17, whose concept willfirst be explained in principle by the use of FIG. 2, and which isrepresented in FIG. 3 directly relating to the web tension of severalwebs B1, B2, B3, B4 in FIG. 1, at least to several webs B1, B2, B3, B4,or partial webs, which together run up on at least one hopper roller 08.

The control system 17 has local and global types of control devices 18and 19, which differ from each other and which have two partial tasks ortwo control processes differing from each other. These two “types” ofcontrol devices 18 and 19 can be embodied as different hardwarecomponents spatially separated from each other, as different softwareprograms communicating with each other, or as two processes, orsub-programs or sub-routines, of a software program. If not explicitlyotherwise mentioned in what follows, the terms local control device 18,and global control device 19, or local control processes 18 and globalcontrol proces 19, are shown with the same reference symbols and shouldbe understood to apply to all of the above mentioned and also to othersuitable possibilities of the conversion of the same. As represented inFIG. 2, the control system 17 has several, represented here as two localcontrol devices 18.1, 18.2, each of which is provided with actual valuesfrom a respective partial process and which generate, by the use oftheir implemented logic, one or more actuating values regarding theobserved partial process. The global control device 19 is of a higherorder than the local control device 18 and receives actual values fromthe partial processes and outputs, by the use of its implemented logic,preset values for the lower-order local control devices 18.1, 18.2, aswell as actuating values directed to the entire process, if required.There is no mutual interaction or communication between the controldevice 18 and 19. Although they can operate simultaneously, inprinciple, they operate independently of each other, even though, inpart, they observe the same process values, or actual values, and theglobal control process 19 creates preset values, or desired values forthe local control processes 18.

Memory devices 21 are also represented in FIG. 2, from which memorydevices 21 starting values can be read into the control device 18, 19prior to the start of the processes. The starting values areadvantageously read in from a common memory unit 21.

At least two measured values from each one of the web paths involved,namely the measured values S1.2, S2.2, S3.2, S4.2 for the web tensions,are provided to the control system 17 in accordance with FIG. 3 forexample from the measuring location 04, configured as a direct measuringroller 04, downstream of the respective printing unit 03, as well as themeasured value S1.3, S2.3, S3.3, S4.3 from the respective measuringlocation 06 located upstream of the hopper inlet, or upstream of theharp 07. In the case of the measured values S1.3, S2.3, S3.3, S4.3, andof the measuring location 06, this also applies to turned partial websassigned to this hopper inlet. In a further development, the web tensionsignal S1.1, S2.1, S3.1, S4.1 for the respective web tension upstream ofthe printing unit 03 can be supplied if needed, as shown indashed linesin FIG. 3. The measurement of the web tension is respectively providedby measuring rollers, around which the web B1, B2, B3, B4 is wound.

The control system 17, at least the control device 18, regulates andoptimizes the web tensions, preferably by using fuzzy logic. The inputvalues, such as for example the measured values S1.3, S2,3, etc. of theweb tensions, which may be appropriately scaled, if required of a web B1are fuzzyfied, i.e. are used as input values for functions defined insections, each of which describes a term such as a linguistic valuerange, for example large, medium or small. The degree to which the inputvalue meets the linguistic meaning of the term or, in case of an overlapof the value ranges, the degree to which it is met, is obtained as afunctional value. In the course of the subsequent defuzzyfication, asolid output value, for example an appropriate signal to an actuatingmember or a new desired value for an actuating member, is generated fromthe degree to which the individual terms of the linguistic variable havebeen met. Depending on the result of defuzzyfication, it is possible toprovide preset values to one actuating member, to another actuatingmember or to several actuating members. Which rules are applied isdetermined by the degree to which the terms of the input values havebeen met. An above-mentioned example with the two input values, forexample with measured values S1.3, S1.2 and with one output value, forexample one signal S.12 to an actuating member, such as for example, theroller/traction group 05 of preset rules, which are available in theform of a table, for example, could be graphically represented as athree-dimensional characteristic diagram, for example. If more inputvalues are entered into a decision process, and/or if it is intended tocreate several output values, the “characteristic diagrams” arecorrespondingly multi-dimensional. The control device 19 need not bebased on fuzzy logic. Instead, it can be configured in other ways, forexample as a PID control device 19. However, the embodiment of controldevice 19 with fuzzy logic is also of advantage here.

As generally represented above, the control system 17 has the twocontrol devices 18 and 19, which are different from each other and whichhave two partial tasks differing from each other. The control device 18regulates the web tension of a single web B1, B2, B3, B4 on its path,and in view of threshold values. The control device 19 sets the tensionlevel, in particular the tension level upstream of the hopper inletroller 08, of the webs B1, B2, B3, B4 which are combined there, inrelation to each other.

The control system 17 has a number of control devices 18, as seen inFIG. 3, which number at least corresponds to the total number of websB1, B2, B3, B4 or to the number of partial webs, which are to be broughttogether. All of the control devices 18 have the same architecture, orare programmed in the same way, and are identified by 18.1, 18.2, 18.3,18.4 for the webs B1, B2, B3, B4 represented in FIGS. 1 and 2. Thecontrol device 19, or the process 19, is assigned to the four controldevices 18.1, 18.2, 18.3, 18.4, or the four processes 18.1, 18.2, 18.3,18.4.

In connection with start-up processes, it is advantageous to presetstarting values in the control system 17 as desired values which, forexample, provide meaningful starting points for a defined web guidance.In the depicted example, it is therefore possible to specify startingvalues S1.11_0, S1.12_0, S2.11_0, S2.12_0, S3.11_0, S3.12_0, S4.11_0,S4.12_0, S0.13_0 and/or S014_0, for the signals S1.11, S1.12, S2.11,S2.12, S3.11, S3.12, S4.11, S4.12, S0.13 and/or S0.14 as tensions oradvances to the control device 18.1, 18.2, 18.3, 18.4, 19. These arepreset in a memory for example, and can be a function of the selectedproduction and/or of the web material.

When operating the control system 17, first every web B1, B2, B3, B4,considered solely by itself, is controlled by use of the control devices18.1, 18.2, 18.3, 18.4, or by use of the processes 18.1, 18.2, 18.3,18.4, in a first partial task, so that the tension at the measuringlocation 06, located upstream of the hopper inlet lies between aminimum, for example MIN=8 dN/m, and a maximum, for example MAX=60 dN/m.A second demand made on the first partial task possibly lies in settingthe stepping, schematically represented in FIG. 4, of the tensions atthe web tension measuring location 14, upstream of the printing unit 03,at the location 04, downstream of the printing unit 03, and at thelocation, 06 upstream of the hopper inlet, or prior to the bringingtogether. In addition, the process-related minimum tensions, for exampleof 8 daN and maximum tensions, of 60 daN must additionally bemaintained. It is therefore the task of the control devices 18.1, 18.2,18.3, 18.4 of the processes 18.1, 18.2, 18.3, 18.4, to adjust thetension of the individual webs B1, B2, B3, B4 at the hopper inlet, andin particular, on their way to it, to the range permitted in principle,and, in addition, to achieve the correct stepping within the web path ofthe web tensions of the individual webs B1, B2, B3, B4, if necessary.

To achieve this partial task, the control devices 18.1, 18.2, 18.3,18.4, in what follows, by way of example, for the control device 18.1 ofthe web B1, are each provided with at least two signals S1.2, downstreamof the printing unit 03 and S1.3 upstream of the hopper inlet orupstream of the bringing together of the webs, of the measured tensionof the same web B1. The control device 18.1 processes these input valuesin the above explained manner by the use of fuzzy logic, and generatesan output signal S1.11, which acts on the actuating member 16 of thedraw-in unit 02. In the simplest embodiment of the control device 18.1,or of the process 18.1, only the two above mentioned input signals S1.2,S1.3 are supplied and an output signal S1.11 is only sent to theactuating member 16 upstream of the printing unit 03. It is optionallypossible to additionally supply the control device 18.1 additionallywith the signal S1.11 for measuring the tension upstream of the printingunit 03, which signal can also be processed in the logical device.

In an advantageous solution, in accordance with the present invention,the control device 18.1 additionally also acts, with the provision of asignal S1.12, on the actuating member 05 downstream of the printing unit03, for example by determining and by specifying suitable advancementvalues. With this embodiment, an improved setting of the course of thetension over the path of the web B1 is possible. In connection withthis, the control concept takes place for example in such a way that itis first attempted, by use of the actuating member 16, to meet therequirements regarding minimum/maximum tension and simultaneously, thedesired course of the tension. If this is not possible by acting on theactuating member 16 alone, the actuating member 05 is also included.

In a substantially self-explanatory manner, FIG. 5 represents theprogression of the control process 18.x by the use of the example of thecontrol process 18.1. Without repeating was has been said above, itbecomes clear that a preset value, in particular for the measuringlocation 06 upstream of the hopper inlet, from the control process 19 isread in. This actual preset value is compared with the last valid oneand, in case of a deviation, one or several of the allocation diagramson which the subsequent calculations are based is changed, and, inparticular, is shifted. The subsequent calculations, for example of ashifting of the desired value for the draw-in unit 02 and/or thecalculation of a draw-in roller displacement of the traction device 05,then take place on the basis of the unchanged or changed allocationdiagrams, or of the unchanged or changed allocation diagram by the useof fuzzy logic, after the measured values S1.2, S1.3 and, if required,S1.1, have been read in. At the start of production of the press,starting values are read in from a memory device 21 instead of thepreset values from the process 19. The partial process prior to theinquiry regarding the press status, i.e. is the press in production? isa part of the initialization of the system. The inquiries are answeredin the diagrams with “true” or “yes” (y) w or “false” or “no” (n). Theconnection with the arrow from the lowest node of the process to thenode prior to the inquiry makes it clear that this is a process which iscontinuously being performed, as long as the press is in production.

The principle of the above mentioned change or shifting of an allocationdiagram is schematically represented in FIG. 6. In a first stage of thediagram, a measured value Sm has first values for weighting of “small”and “medium”. After the allocation functions have been shifted, definedin sections, the measured value Sm is faced with different weightedvalues “small” and “medium”. This change in the weighting is nowreflected in the total view of all fuzzy rules and, in the end, possiblyleads to a shifting of the desired values with respect to the actuationvalue in question, here, for example, the actuating value S1.11 for thedraw-in unit 02.

In a second partial task, a check is made by the control device 19, orby the control process 19, whether upstream of the harp 07 the tensionsof the webs B1, B2, B3, B4, which are to be combined, are in the desiredrelationship with respect to each other, and this is controlledaccordingly. Thus, for example, the lowest web B1, B2, B3, B4 whichcomes to rest on the traction roller 08, in this case the web B3, shouldhave a greater tension than the one above it, etc. Therefore, the secondtask is to step, or to align, the mutual tensions in the webs B1, B2,B3, B4, which are to be conducted, on top of each other, in the area ofthe hopper inlet. Here, the minimum requirement, that S_(n)≧S_(n+1),applies to all S1.3, S2.3, S3.3, S4.3, etc., if n identifies a web B1,B2, B3, B4, and n+1 identifies the outwardly adjoining web B1, B2, B3,B4. As a side constraint, the following applies to all webs B1, B2, B3,B4: MAX≧S₁≧S₂≧S₃≧S₄≧MIN, if the index characterizes the sequence of thewebs B1, B2, B3, B4 from the inside to the outside. In addition, a rulefor the optimum condition advantageously exists which rules states thatS_(n)≧S_(n+1)+Delta S, wherein Delta S=2 dan/m, for example.

In the second partial task, or the first control process 19, thetensions in the various webs are varied, for example, in such a way thatthe tension of all of webs B1, B2, B3, B4 upstream of the hopper inletroller 08 lies within the tolerance range, shown in FIG. 4, upstream ofthe hopper entry vTE. For this purpose, the signals S1.3, S2.3, S3.3,S4.3 of the measured values of the web tension are supplied to thecontrol device 19 parallel with the control device 18.1, 18.2, 18.3,18.4. In a further development, fuzzy logic is also the basis for thecontrol device 19, or the control process 19, by the use of which presetvalues for the control devices 18.1, 18.2, 18.3, 18.4, as well assignals S0.13 and S0.14 for the actuating members 08 and 10, which worktogether with the strand 13, are generated as output values from theinput values, signals S1.3, S2.3, S3.3, S4.3.

FIG. 7 represents, again in a self-explanatory way, the flow of thecontrol process 19. As can be seen, it is possible to preface the actualpartial process for the matching of the web tensions Sx.3, among eachother, with a partial process which, as represented in FIG. 7, checksthe total web tension level on the basis of the individual measuredvalues Sx.3 and, if required, raises or lowers the total level of all ofthe webs or partial webs running over the roller 08 by adjusting, forexample, the advance of this hopper inlet roller 08. The partial processcontains the steps of reading in the measured values, checking the totalweb tension, and, depending on the result, of calculating and outputting(n) the shifting of the hopper inlet roller, or to leave it as it is(y).

In case of a deviation (f) of the adjustment of the tensions among eachother from the preset relationship, MAX≧S1.3≧S2.3≧S3.3≧S4.3≧MIN, and/orthe threshold values, preset values are calculated for the respectivecorrection processes 18.x, or for the respective correction process18.x, in particular for the measuring location 06 upstream of the hopperinlet, and are output. Here, the calculation can also take place by theuse of fuzzy logic wherein, for example, again allocation diagrams,which are the basis of the calculation, are shifted in accordance withthe deviations. At the production start of the press, starting valuesfrom a memory device 21 are read in instead of the preset values fromthe process 19. The partial process prior to the inquiry regarding thepress status, in production? is a part of the initialization of thesystem.

In an advantageous embodiment of the present invention, the controldevice 19, or the control process 19, has no direct influence on theactuating members 16, 05 which are assigned to the individual webs B1,B2, B3, B4, but provides preset values S1.3 d to S4.3 d to the controldevices 18 from the signals S1.3 to S4.3 by the use of itscharacteristic diagram. This preset value merely relates to a tension tobe maintained upstream of the hopper roller 08 for each web B1, B2, B3,B4, i.e. to a desired value S1.3 d to S4.3 d for the tensions to bemaintained, for example, at the measuring locations 06 (see, forexample, the diagrammatic illustration of FIG. 3). These preset values,for example because of a change in the position and/or form of theterms, or of the input values in the course of the fuzzyfication, areentered in the control device 18.x, as discussed above. Therefore, anactuating member 02, 05, 16 assigned to an individual web B1 to B4 isnot randomly addressed by two different processes, which would result inan unsteady or even unstable control behavior. In contrast to this, therequest from the control process 19 is taken into consideration in thecontrol process 18.x. The advantageous performance of this partialprocess in the control device 18.x, in the form of fuzzy logic, nowmakes it possible for the request or the preset value from the controldevice 19 not necessarily having to be performed exactly as prescribed,but instead being performed within the scope and in view of the entirecontrol task of the control device 18.x. Only the allocation diagramsregarding the preset values from the control device 19 are shifted, andthese newly weighted criteria are taken into consideration whendetermining the optimal, or at least the permissible total state. Theconnection with the arrow from the lowest node of the process to thenode prior to the inquiry of the press status, as seen in FIG. 7, makesit clear that this is a process which is continuously performed as longas the press is in production.

These two control processes 18 and 19, or the partial tasks connectedtherewith, are cyclically repeated and, corresponding to the measurementresults and the results from the logical device, the units affecting theweb tension, for example the traction rollers 16, 05, 08, 10, or other,not specifically represented, compensating rollers, etc. are charged,Besides the above mentioned units, such as traction rollers in thedraw-in unit 02 and/or one or several traction rollers 16, 05, 08, 10,these units affecting the web tension can also additionally be devicesin the roll changer 01 and/or devices in the folding apparatus 11. Whathad been said above in connection with FIG. 3 then must be complementedby appropriate signals, for example signal S1.10, for the roll changer01, or by not specifically represented signals for the folding apparatus11.

In an advantageous embodiment of the present invention, the control ofsuch units, by use of the control system 17, takes place while taking apriority into account. For example, as explained above, in a firstpriority, the entry of the desired value by the control system 17 isperformed only for the draw-in unit 02. If the two above mentioned taskscannot be performed with this step alone, the traction roller 05downstream of the printing unit 03 is acted upon. If necessary, in athird step it is permissible to influence the hopper inlet roller 08.However, in the course of this, the level of all of the affected websB1, B2, B3, B4 is shifted. The actuating members, such as the tractionroller 05 or the hopper inlet roller 08, are only used in case theglobal web tension of all of the webs B1, B2, B3, B4 is not correct, orif the actuating range of the draw-in unit 02, or its actuating member16, is not sufficient for the desired web tension.

If the requirement of the second partial step, i.e. the desired webtension stepping, cannot be achieved, the logic of the control system,in particular the logic of the control device 19, can be embodied toreach a state which approaches, as closely as possible, an ideal state.Still acceptable limits for the deviation, either relative or absolute,can be preset and, if necessary, can be changed. In addition, in anadvantageous further development of the present invention, the controlsystem can be configured to issue a cautionary advice in the case of toogreat a deviation from the permissible tension profile of a web or thestepping, all of the webs in respect to each other, and, if required, incase of an impermissibly large deviation, to cause the stop of theprocessing press.

However, in the simplest embodiment, the control system 17 operates withtwo types of measurement of the tension of each of the involved webs B1,B2, B3, B4, namely web tension measurements respectively downstream ofthe printing unit 03 and upstream of the hopper inlet, wherein thecorrective action takes place, respectively, first at the draw-in unit02 and, if required, in a second step in the area of the traction roller05.

As mentioned previously above, following the longitudinal cutting of aweb B1, B2, B3, B4, several partial webs, all of which are assigned to aroll changer 01, can be conducted to the hopper 09 along paths whichdiffer from each other. In this case, the tension of each partial web isdetermined upstream of the hopper inlet, for example, each at its ownmeasuring location 06. These measured tension values, which are assignedto a common roll changer 01, for example S1.3 a and S1.3 b, are linked,either before they are conducted to the control system 17, or in thecontrol system 17, i.e. in the control device 18, as well as in thecontrol device 19, to form a value, and are, for example, averaged withor without weighting. The resulting value is employed as an actual valuefor the control. This linkage can be integrated into the respectivecontrol devices 18, 19 as a logical component 22, or as a sub-process22, which is represented by dashed lines by way of an example.

Preferably the roll changer 01 and the draw-in unit 02 have a closedcontrol loop, in addition to the control system 17, which closed controlloop is provided with a specified desired value by the control system17. The traction rollers 05, 08, 10, 16 are controlled by the controlsystem 17 only in respect to their advancement; i.e. their number ofrevolutions, or angular position. The units involved are specified bytheir advantageous embodiments for influencing the tension.

The draw-in unit 02 has a closed loop control. The provision of presetdesired values by the control system 17, and in particular by thecontrol device 18, is thus dependably maintained. Draw-in unit 02 actson the entire web B1, B2, B3, B4 and is considered to be the mostimportant actuating member. In an advantageous embodiment, the draw-inunit 02 has a roller as the actuating member 16, which roller 02 can bemoved counter to the tractive force of the web B1, B2, B3, B4 and which,by the use of pressure means of a specified pressure force, counteractsthe tractive force of the web. In this case, no separate measuringlocation 14 is required, provided the correlation between the chargedpressure and the resultant web tension is known.

By changing the advancement with relation to the paper web speed, thetraction roller 05 can act on the web tension of the actual web B1, B2,B3, B4, and here constitutes the last chance, upstream of the hopperinlet roller 08, for influencing an individual web B1, B2, B3, B4 withregard to its tension, or stepping.

By changing the advancement, in relation to the paper web speed, thehopper inlet roller 08 can act on the web tension of all of the webs B1,B2, B3, B4.

The folding traction roller 10 can also act on the web tension of all ofthe webs B1, B2, B3, B4 by a change of its advancement, in relation tothe paper web speed. It has direct effects on the cutting registration.

A modular construction, for example, allows the extension of the controlto several webs, in case of a separate solution by the use of thehardware, it is merely necessary to add a further control device 18, forexample a fuzzy SPS with a program, to each further web B1, B2, B3, B4.It is furthermore necessary to inform the program of the control device19, for example the master SPS, that it must incorporate a further webB1, B2, B3, B4.

In a pure software solution for the control devices 18 and 19, it isonly necessary, in case of an expansion by one web B1, B2, B3, B4, toincrease the software by one control process 18.x and to inform theprogram of the control process 19.

Control by the control devices 18 and 19 can run purely sequentially,but can also run parallel, viewed chronologically wherein, however, inview of the tension to be set upstream of the hopper inlet roller 08,for example at the measuring location 06, the control is hierarchicallyconstructed and the control device 19 is of a higher order than thecontrol devices 18.

In an advantageous further development, in accordance with the presentinvention, the control system 18 is embodied in such a way that asetting for a defined configuration of the print application, found byuse of the control system 17, a web path and/or a defined product, canbe transmitted as a specified value to the memory device, so that thesecan be read in as starting values in the future in an identical or in asimilar production situation. For this purpose, the takeover of theproduct or production values takes place from the press control and/orproduct planning. The takeover as new starting values can be triggered,for example, as a result of a decision of the operators, or by thesystem itself if the control and/or the control system are configured asa self-learning system in respect to this function.

While preferred embodiments of methods and of a device for theregulation of the web tension in a multi-web system, in accordance withthe present invention, have been set forth fully and completelyhereinabove, it will be apparent to one of skill in the art that variouschanges in, for example, the overall size of the printing press, thedrives for the rollers and the like could be made without departing fromthe true spirit and scope of the present invention which is accordinglyto be limited only by the appended claims.

1. A method for controlling web tensions in a multi-web systemincluding: providing at least first and second separate webs; passingsaid first web through a processing step and through a traction element;providing a first local tension control process for controlling webtension in said first separate web; measuring said first web's tensionand generating a first web tension measurement value; controlling saidfirst web's tensions using said first local tension control process togenerate a first local tension control value; said first local tensioncontrol value being set, initially, at a first local preset tensionvalue; passing said second web through a processing step and through atraction element; providing a second local tension control process forcontrolling a web tension in said second web; measuring said secondweb's tension and generating a second web tension measurement value;controlling said second web's tension using said second local tensioncontrol process to generate a second local tension control value; saidsecond local tension control value being set, initially, at a secondpreset tension value; combining said at least first and second separatewebs into a web strand; wherein said first and second local tensioncontrol processes control said web tension in each of said at leastfirst and second separate webs prior to combining said at least firstand second webs into said web strand; providing a global tension controlprocess for controlling relative web tension between said first andsecond separate webs; wherein said global tension control process isresponsive to said first web tension measurement value and said secondweb tension measurement value; generating, in said global tensioncontrol process, at least one desired tension value for one of saidfirst web's tension and said second web's tension; said desired tensionvalue being generated in response to a comparison of said first webtension measurement value 3 and said second web tension measurementvalue with regard to a required relationship therebetween; out-putting,from said global tension control process, at least one desired tensionvalue to one of said first and second local control processes inresponse to the measured web tension in one of said first and secondseparate webs deviating from a selected tension level; and controllingweb tension in said at least first and second separate webs using atleast one of said traction elements.
 2. A method for controlling webtensions in a multi-web system, including: (a) providing at least firstand second separate webs; (b) passing said first web through aprocessing step and through a traction element; (c) providing a firstlocal tension control process for controlling web tension in said firstseparate web; (d) measuring said first web's tension and generating afirst web tension measurement value; (e) controlling said first web'stension using said first local tension control process to generate afirst local tension control value; said first local tension controlvalue being set, initially, at a first local preset tension value; (f)passing said second web through a processing step and through a tractionelement; (g) providing a second tension control process for controllinga web tension in said second web; (h) measuring said second web'stension and generating a second web tension measurement value; (i)controlling said second web's tension using said second local tensioncontrol process to generate a second local tension control value; saidsecond local tension control value being set, initially, at a secondpreset tension value; (j) combining said at least first and secondseparate webs into a web strand; (k) wherein said first and second localtension control processes control said web tension in each of said atleast first and second separate webs prior to combining said at leastfirst and second webs into said web strand; (l) providing a globaltension control process for controlling relative web tension betweensaid first and second separate webs; wherein said global tension controlprocess is responsive to said first web tension measurement value andsaid second web tension measurement value; (m) generating, in saidglobal tension control process, a relative tension comparison controlvalue in response to said first web tension measurement value and saidsecond web tension measurement value; said relative tension comparisoncontrol value being set, initially, at a global preset relative tensionvalue; (n) out-putting, from said global tension control process, atleast one relative tension comparison control value to one of said firstand second local control processes in response to the measured webtension in one of said first and second separate webs deviating from aselected tension level; and (o) controlling web tension in said at leastfirst and second separate webs using at least one of said tractionelements.
 3. The method of claim 2, wherein step (l) further comprises:providing, in said global tension control process, means for controlling(a) total web tension in said web strand comprising at least first andsecond separate webs and (b) relative web tension between said first andsecond separate webs; wherein said global tension control process isresponsive to said first web tension measurement value and said secondweb tension measurement value.